The SX100's scroll dial seems nicer in theory than in practice; frequently, when trying to change the shutter speed, I would accidentally click and end up changing the focus or ISO settings. It takes a while to get accustomed to the feel to prevent that from happening.
Although the SX100 has some color reproduction issues with reds--these flowers are a completely different shade in reality--it nevertheless produces vivid, saturated colors without going overboard. In general, photos looked evenly and correctly exposed.
At its widest angle, the SX100 displays some--but not a lot--of barrel distortion. Because the distortion is reasonably symmetrical, it's less disturbing as a lens artifact. (Lines overlaid in Photoshop.)
Fringing doesn't seem to pose a significant problem for the SX100, but there is some and what's there is colorful: In addition to purple and yellow, my photos also display magenta halos on high-contrast borders.
For a comparatively inexpensive camera, the SX100 displays a pretty good noise profile. Detail only begins to degrade at ISO 400 and is still usable at ISO 800. At ISO 1,600, though there's quite a bit of smeariness, there's still very little color noise (for the camera's price class).